The goal of the proposed research is to develop a murine model in which to define the involvement of natural killer (NK) cells and HSV-specific cytotoxic T lymphocytes (CTL-HSV) in the development of HSV-1 skin and corneal lesions. The project is based on the recent findings that thoracic duct lymphocytes (TDL) from alloimmunized mice contain CTL but no NK cells or NK precursors. These TDL also contained lymphocytes that suppress NK activity (NK-suppressor cells). We observed that a dose of HSV-1 that failed to produce clinical signs of infection when injected into the hind footpad of A/J mice produced severe periocular skin and corneal lesions when applied topically to the cornea. We noted that following corneal infection the mice: (1) did not demonstrate the early activation of NK activity in the peripheral blood that was observed in footpad infected mice; (2) produced CTL-HSV activity in the regional lymph nodes (RLN) with subsequent appearance in the blood coinciding with the appearance of skin lesions; (3) did not develop CTL activity in the spleen; and (4) developed lesions first in the skin and later and at a lower frequency in the cornea (a site that is not initially in direct contact with the immune system). Based on these observations we hypothesize that early activation of NK cells in the blood may be important in preventing HSV lesions; and that CTL-HSV activity may actually contribute to the development of lesions. Extending the findings, one might prevent the appearance of CTL-HSV in the peripheral blood of infected mice without depleting NK cells by cannulating the thoracic duct (TD). Mice will undergo TD drainage on days 6-13 following corneal HSV challenge (corresponding to the period of CTL-HSV activity in the blood). We will determine if TD drainage prevents the appearance of CTL-HSV activity in the blood). We will determine if TD drainage prevents the appearance of CTL-HSV in the blood and also observe cannulated and sham cannulated mice for clinical signs of infection. The efficaciousness of TDL from cannulated mice as a source of CTL that lack NK cells and NK precursors will be tested. TDL will be collected from alloimmunized mice as a potential source of NK-suppressor cells lacking CTL-HSV and NK activity. Peripheral blood lymphocytes will be obtained on day 3 after HSV footpad challenge as a source of activated NK cells and tested for contaminating CTL. This project will thus lay the groundwork for future adoptive transfer studies in which we will attempt to prevent HSV lesions by a combination of TD cannulation and adoptive transfer of CTL-HSV that lack NK cells or NK precursors, or activated NK cells that lack CTL-HSV.